Bulky yarn and process for preparing same



p 1964 J. EARNSHAW 3,146,574

BULKY YARN AND PROCESS FOR PREPARING SAME Filed Aug. 8, 1961 INVENTOR JOHN EARNSHAW ATTORNEY United States Patent 3,146,574 BULKY YARN AND PRQCESS FOR PREPARING SAME John Earnshaw, Baildon, England, assignor to E. I. du

Pont de Nemours and Company, Wilmington, Del., a

corporation of Delaware Filed Aug. 8, 1961, Ser. No. 130,160 Claims priority, application Great Britain Aug. 12, 19% 13 laims. (Cl. 57l40) This invention relates to bulky, extensible yarns and to a process for preparing such yarns.

Bulky is a term used to describe yarns which are of large cross-section in relation to their weight per unit length. Yarns of wool are bulky generally speaking because wool fibers are not essentially straight, but have a natural crimp or curl. Thus, Wool yarns do not consist of essentially linear parallelized fibers but the natural curl in the wool fibers causes wool yarns to be of lower density and higher covering power than would be the case if the fibers were essentially linear and parallelized. This characteristic is sometimes referred to as voluminous or lofty, but is referred to throughout the specification and the claims as bulky. Synthetic fibers, when extruded through a conventional spinning jet, are not generally bulky, but consist of essentially straight, smooth continuous filaments having no convolutions, loops, rings, crimps, curls or whorls, unless a special treatment is given to the continuous synthetic filaments in order to affect the physical structure of the filament. Unless such a special treatment is carried out on the synthetic fibers, synthetic fiber yarns generally consist of essentially straight parallelized fibers whether they are continuous filaments or staple fibers. It has for some time been considered desirable to impart bulkiness to yarns spun from synthetic fibers, and much inventive effort has been devoted to treatment of synthetic fibers and yarns in order to impart this bulky characteristic.

According to the present invention, there is provided a process for preparing yarn from crimp-settable fiber, comprising incorporating a minor proportion of fiber of high shrinkage power, shrinking the fiber of high shrinkage power under substantially tensionless conditions so as to cause the crirnp-settable fiber to crimp, setting the crimp in the crimp-settable fiber, and treating the yarn so as to neutralize the inextensible nature of the shrunken fibers.

By crimp-settable fiber is meant any fiber to which it is possible permanently to impart a crimp. By crimp is meant any physical deformation imparted to the fiber, for instance, any type of convolution, loop, ring, curl or whorl, whether the physical deformation is imparted by mechanical or other means, such as chemical. By permanently is meant that, after crimp-setting, the fibers natural configuration will be that resulting from the crimping; for instance, it is possible to straighten a crimped fiber by applying a tension to each end but, when the tension is released, the fiber will return to its crimped configuration. It should be understood that, although the term permanent has ben used, it may be possible to reset the fiber with a different crimp or in an uncrimped configuration by appropriate treatment; for instance, the permanent crimp imparted to a thermoplastic fiber by suitable conditions of heat can be removed or altered by reheating the fiber to the same or a higher temperature 3,146,574 Patented Sept. 1, 1964 ice and imparting a fresh configuration. It should also be realized that the configuration of any individual fiber in the yarn will be affected by the presence of the other fibers, so that the inclination of the fiber to return to its crimped configuration may be affected by the presence of the other fibers in the yarn.

Thermoplastic fibers are preferred crimp-settable fibers, the crimp being set by suitable conditions of heat, with steam if desired, using conventional crimp-setting processes. Any natural or synthetic plasticizable filamentary material, may be used including thermoplastic materials such as polyamides, e.g., poly(epsilon-caproamide) and poly(hexamethyleneadipamide); cellulose esters; polyesters, e.g., terephthalate esters of ethylene glycol and of transparahexahydroxylylene glycol; polyalkylenes, e.g., polyethylene, and polypropylene; polyvinyls and polyacrylics, e.g., polyacrylonitrile as well as copolymers of any of the foregoing. The commercial or trade identity of a number of these fibers include such common ones as nylon polyamides, Dacron (trademark for Du Ponts polyester fiber) and Terylene (trademark for Imperial Chemical Industries polyester fiber) polyesters, and Orlon (trademark for Du Ponts acrylic fiber), Acrilan" (trademark for Chemstrands acrylic fiber) and Courtelle (trademark for Courtaulds Ltd.s acrylic fiber) copolymers of polyacrylonitrile. Polyacrylonitrile fibers have been found especially suitable in previous bulking processes, and are preferred according to the present invention.

Although thermoplastic fibers are preferred and are at present the most readily adapted to crimp-setting, the invention is not confined to thermoplastic fibers. It is Well known that crimp can be imparted and/ or set by chemical treatment, such as by the use of chemical swelling and/or shrinking agents. Crimp-setting by such methods is within the scope of the present invention.

It is preferred that the crimp-settable fiber has little or no capacity to shrink, as will be explained in more detail hereinafter.

By fiber of high shrinkage power, is mean-t not merely that the fiber has a capacity to shrink or contract, but that importantly, when present in minor proportion in a yarn consisting predominantly of fibers having a substantially lower capacity to shrink under the conditions which will cause shrinkage in the fiber of high shrinkage power, the contraction of the fiber of high shrinkage power will occur with sufiicient force to reduce the length of the yarn itself, thus causing the nonor less-shrinkable new shortened length of the yarn. Thus, after shrinking, fibers to take up new configurations so as to adapt to the the yarn will comprise the minor proportion of fiber (of initiallyhigh shrinkage power, but now shrunken), the configuration of which will be essentially straight, and the predominant proportion of crirnp-settable fiber in a crimped and therefore bulky configuration. It should be understod that the whole purpose is to obtain a differential shrinking effect, so that the shrinkage power of the selected shrinking fiber should be high with respect to the capacity of the selected crimp-settable fiber to shrink, and to the force required to shrink the yarn comprising the selected crirnp-settable fibers. The shrinkage power could be termed retractive efiect.

So as to get a good differential shrinking effect, it will clearly be of assistance to use a crirnp-settable fiber having little or no capacity to shrink, and for this reason such crimp-settable fibers are preferred. It is possible to prepare relaxed crimp-settable fibers from those mentioned above being capable of shrinking less than 3%, and such fibers having very low capacities to shrink have been found very useful in the process of the invention.

The invention should be contrasted with previous efforts to prepare bulky yarns by shrinking, such as for instance in US. Patent No. 2,810,281, where the different fibers do not have a high enough differential shrinkage and the shrinkable fiber is therefore used in large proportions, and the yarn is not treated so as to neutralize the inextensible nature of the shrunken fiber. The differential shrinkage of the two types of polyacrylonitrile fiber in US. Patent No. 2,810,281 is of the order of whereas the differential shrinkage between the tWo types of fiber used in the examples of the present invention is of the order of to at least. The final yarns prepared as described in U.S. 2,810,281 have of inextensible fiber, and are therefore themselves inextensible. Indeed, US. 2,810,281 emphasizes the importance of including enough of this inextensible component so as to ensure that their final composite yarn has adequate tensile strength.

Many synthetic fibers have a high capacity to shrink imparted by a stretching process known as cold-drawing or stretch-spinning, the process generally taking place almost immediately after the synthetic fiber is extruded as a continuous filament from the spinning jet. Such colddrawn fibers are dimensionally unstable in that, on heating to an appropriate temperature for the particular material, the fibers will shrink to substantially their original nature when extruded from the spinning jet. Although many cold-drawn synthetic fibers have a high shrinkage capacity, on account of the cold-drawing process, the shrinkage power is not always as high as is required for the process of the present invention, depending on the selected crimp-settable fibers. Cold-drawn polyvinyl chloride fibers are preferred as fibers of high shrinkage power according to the invention. Examples of such fibers that have been available commercially have been sold under the following trademarks: Fibravyl (trademark for Soc. Rhovyls high shrinkage polyvinyl chloride fiber), which can contract by as much as to in length, and Retractyl 30 (trademark for Soc. Rhovyls medium shrinkage polyvinyl chloride fiber), which can contract by about 35%. Other suitable fibers include polyvinylidene chloride fibers, and copolyrners of vinyl chloride and/or Vinylidene chloride especially with acrylonitrile.

The higher the shrinkage power of the fiber, generally speaking, the better the fiber is for the purposes of the present invention. This is because there must be enough or" the fiber of high shrinkage power to achieve the necessary shrinkage of the yarn so as to achieve the desired crimp in the crimp-settable fiber. The lower the shrinkage power, the larger the amount of the fiber of high shrinkage power that will be necessary in order to achieve the necessary shrinkage of the yarn and crimping of the crimp-settable fiber. The shrunken fiber (initially of high shrinkage power) in the final bulky yarn does not substantially contribute to the bulky properties of the yarn (except historically insofar as by shrinking it has caused the crimp-settable fiber to crimp and become bulky) and becomes at this stage undesirable in the yarn in view of its inextensible nature. Thus it is generally desired to have as low a proportion of the fiber of high shrinkage power as possible, consistent with the necessity of achieving the necessary shrinking effect on the yarn as a whole. As can be seen from the examples, it is possible to obtain good commercial results using predominantly polyacrylonirtile fiber yarns containing 2 to 10 percent by weight of polyvinyl chloride as fiber of high shrinkage power. The precise proportions will always depend on the individual characteristics of the particular yarn and its components, especially the nature of the crimp-settable fiber, the nature of the fiber of high shrinkage power and the number of fibers in the crosssection of the strand at any particular point. It will be understood that it is generally more necessary to have a higher proportion of fiber of high shrinkage power in strands having a small number of fibers per unit crosssection, on account of the difficulty in ensuring that the fibers of high shrinkage power are uniformly distributed, and the necessity of obtaining overall shrinkage of the yarn as a whole.

As has already been pointed out, it will generally be desirable to keep the proportion of fiber of high shrinkage power as low as possible, since it does not substantially contribute to the bulk of the final yarn. Further, the greater the amount of such fiber, the more effort will have to be expended to neutralize its inextensible nature. Generally it will not be considered desirable to use more than 20 percent by weight of the fiber of high shrinkage power, but, depending on the intended end-uses for the yarn it may be possible and suitable to use higher proportions, for instance up to 25% and 30% by weight. If the fiber of high shrinkage power is inexpensive, the upper limit to its proportion will not be of so much economic importance, especially if, like polyvinyl alcohol, it can be dissolved away so that the final yarn will consist only of crimped fiber.

As has already been indicated, once the crimp has been imparted to the crimp-settable fiber by the shrinking of the fiber of high shrinkage, and the crimp has been set, the presence of the shrunken fiber (initially of high shrinkage power) becomes undesirable in view of its inextensible nature, which must therefore be neutralized by appropriate means. These means will depend upon the nature of the fiber. Generally it has been found according to the present invention that the yarn may be stretched within carefully controlled limits, and this method is presently preferred for polyvinyl chloride fiber. The effect of the carefully controlled stretching is to displace the shrunken fibers relative to each other and to the crimped fibers, and in many cases even to break the shrunken fibers. When the stretching tension is released, the stretched yarn will contract owing to the presence of the crimped fiber; henceforth the yarn will be extensible owing to the presence of the crimped fiber, the inextensible nature of the shrunken fiber having been permanently neutralized by this stretching.

There is also provided according to the invention a bulky extensible yarn comprising predominantly fibers set with a random 3-dimensional crimp and a minor proportion of substantially non-crimped fibers, the substantially non-crimped fibers being located substantially centrally within the strand without constituting a continuous core. The fibers set with a random S-dimensional crimp are the crimp-settable fibers used in the process of the present invention, while the substantially non-crimped fibers are the shrunken fibers initially of high shrinkage power. These yarns according to the invention have an appearance similar to that of conventional spun yarns, but have a high extensibility or recoverable elongation, e.g., of the order of 2045%. The term extensibility is used instead of elasticity to avoid any connotation of an elastomeric yarn.

It will be understood that yarns according to the invention may, if desired, contain additional fibers of a type other than the crimp-settable fibers and the fibers of high shrinkage power. Depending on the properties of these additional fibers, the characteristics of the resulting yarns can be modified. It can certainly be envisaged that a useful yarn within the scope of the invention could be obtained by using two or more different types of crimpsettable fiber having different shrinkage capacities, by way of example. It can also be envisaged that two or more kinds of fibers of high shrinkage power can be used. By carefully choosing appropriate fibers therefor, and by carefully controlling the conditions of the process of the invention, it will be possible to prepare yarns having predetermined characteristics of bulk and extensibility.

The shrinking may be carried out in any desired manner. It is important, however, that the yarn should be tensionless, so far as possible, in order to allow uniform shrinking of the fiber of high shrinkage power. A convenient means of shrinking is by steaming in an autoclave, the hanks of yarn being laid on shallow trays in order to ensure that tensionless conditions are obtained.

The present invention will be more fully described with reference to the following drawings in which:

FIGURE 1 is a diagrammatic elevation of the apparatus for applying stretch tensioning to the yarn;

FIGURE 2 is a diagrammatic illustration of a short length of the original as-spun yarn from which the bulky yarn of the present invention is prepared;

FIGURE 3 illustrates the bulky, inextensible yarn obtained by shrinking the high shrinkage fiber in the length of yarn shown in FIG. 2; and

FIGURE 4 illustrates the bulky, extensible yarn of the present invention.

Referring now to FIG. 1, a hank of the yarn 11), after shrinking in the autoclave as hereinbefore described, is placed on a hank holder 12 mounted on a spindle 11 carried on a framework of the machine. The yarn is led through a yarn guide unit 14 (to prevent any overrun) around a roll 16. The roll 16 may be of any suitable material and is covered with a sleeve or cot of rubber or synthetic material possessing a high enough coefiicient of friction to prevent the yarn slipping over its surface. The roll 16 is mounted on a spindle attached to the framework of the machine and is free to revolve, but this freedom is controlled to any desired extent by a braking device which applies frictional pressure to the roll 16 through a spring-loaded screw 18.

The over-run prevention yarn guide unit 14 is so placed as to guide the yarn passing through it into a position where it may be passed for one to one and one-half full turns around roll 16.

The yarn from the roll 16 is then taken through a nip formed by the two rolls 20 and 22, each of which is covered with a cot or sleeve of rubber or similar resilient material. The roll 20 is fixed concentrically to a shaft 24 which is mounted between bearings carried by the framework of the machine. One end of the shaft 24 is extended and on this extension is fixed a driving pulley 26. The shaft 24 is driven by belt or chain through pulley 26 by an electric motor 28. The roll 22 is a simple pressure roller free to revolve upon its spindle 31?. The spindle 30 is mounted in a cradle and the whole assembly of roll and cradle is so mounted in the machine framework as to permit the roll 22 to be brought into longitudinally parallel contact with the roll 26. The cradle assembly is spring loaded when the rolls 20 and 22 are brought into contact, thus forming a nip between the two rolls.

The distance from the center of roll 16 to the nip of the rolls 20 and 22 is slightly in excess of the longest staple fibers contained in the yarn being stretch tensioned.

As the roll 20 is driven by the motor 28, the nip between the rolls 20 and 22 draws the yarn forward against the braking action of the roll 20, which braking action is adjusted by the screw 18.

The yarn from the rolls 20 and 22 is led into a can 32 in which it is coiled in a tensionless condition.

In practice, the degree of friction applied to roll 16 may be stated as being controlled between a condition of no resistance and an upper limit, which, if applied, will cause the yarn passing through the machine to break down. Thus the yarn passing through the machine may, in a closely controlled way, be stretch tensioned to any desired degree.

The braking applied to the roll 16 should ensure that the inextensible nature of the shrunken fibers is neutralized.

An alternative method of braking is to use another pair 6 of nip rolls operating at a speed less than that of the rolls 20 and 22.

Although this apparatus has been described in relation to treatment of a single yarn in a discontinuous manner, it can be readily adapted for treating multiple ends and a continuous process, using warpor tow-handling techniques, when a pair of rolls is likely to be preferred over the braking roll shown in the drawing.

Referring now to FIGURES 2, 3, and 4, FIG. 2 represents an as-spun yarn comprised of a blend consisting of a minor proportion of high shrinkage fiber and a major proportion of low shrinkage, crimp-settable fiber. Since the fibers are intermingled, the two types of fibers are not readily discernible in the illustration. The twist introduced into the yarn by the usual spinning methods is indicated. As shown in FIG. 3, after shrinking the high shrinkage fibers, the crimp-settable fibers are convoluted, thereby providing a bulky yarn. Asillustrated in FIG. 3, the length of yarn of FIG. 2 contracted approximately 50% of the original spun length during the shrinking treatment. After processing the yarn of FIG. 3 on apparatus of the type shown in FIG. 1, the bulky, extensible yarn obtained, which is approximately 70% of the original spun length, is illustrated in FIG. 4. While not forming a continuous core, the substantially non-crimped, high shrinkage fibers are located substantially centrally within the bulky yarn.

The invention will be further illustrated in the following examples, all parts and percentages being by weight except when otherwise indicated.

EXAMPLE I A blend was prepared composed of 10% of Fibravyl (trademark for Soc. Rhovyls high shrinkage polyvinyl chloride fiber) and 90% acrylic fiber (C0urtelle, 6 denier (trademark for Courtaulds Ltd.s acrylic fiber) The fibers were thoroughly mixed, then drawn and spun on open drawing followed by both ring and fiyer spinning on the worsted system. Any other system of staple spinning may be used, however. The resultant yarns were 1/5s W.C. (worsted count) and 2/ 16s W.C. The singles yarns were spun with Z twist and, where plied, S twist was used. These conditions were also followed in the subsequent examples.

A blend was prepared composed of 8% Fibravyl (trademark for Soc. Rhovyls high shrinkage polyvinyl chloride fiber) and 92% unstretched acrylic fiber (Courtelle, 6 denier (trademark for Countaulds Ltd.s acrylic fiber) Yarns produced from the blend and subjected to steaming in an autoclave as in Example I were shrunk to about 53% of their original spun length and then, after stretching, contracted to about of the original length to give yarns capable of recoverable extension of about 30%.

EXAMPLE III A blend was prepared composed of 4% Retractyl 30 (trademark for Soc. Rhovyls medium shrinkage polyvinyl chloride fiber) and 96% unstretched 6 denier acrylic fiber of the type described in US. Patent 2,837,501.

Yarns produced from the blend and subjected to steaming in an autoclave as in Example I were shrunk to about 62% of their original spun length and then, after stretching, contracted to about 80% of their original length to give yarns capable of recoverable extension of about EXAMPLE IV A blend was prepared composed of 2% Retractyl (trademark for Soc. Rhovyls medium shrinkage polyvinyl chloride fiber) and 98% unstretched 6 denier acrylic fiber of the type described in US. Patent 2,837,501.

Yarns produced from the blend and subjected to steaming in an autoclave as in Example I were shrunk to about 67% of their original length and then, after stretching, contracted to about 80% of their original length to give yarns of recoverable extension of about 25%.

EXAMPLE V A blend was prepared composed of 8% Fibravyl (trademark for Soc. Rhovyls high shrinkage polyvinyl chloride fiber) and 92% nylon (British Nylon Spinners nylon 66, 3 denier).

The fibers were thoroughly mixed and spun as in Example I and the spun yarns in hanks under tensionless conditions were subjected to steaming in an autoclave at 295 F. for ten minutes. The yarns were shrunk to about 50% of their original spun length and then, after stretching, contracted to about 70% of their original length to give yarns of recoverable extension of about 40%.

EXAMPLE VI A blend was prepared composed of 8% Retracyl 30 (trademark for Soc. Rhovyls medium shrinkage polyvinyl chloride fiber) and 92% Terylene, 4 denier (trademark for Imperial Chemical Industries polyester fiber).

Yarns produced from the blend and subjected to steaming in an autoclave as in Example V were shrunk to about 65% of their original spun length and then, after stretching, contracted to about 75% of their original length to give yarns of recoverable extension of about 30%.

EXAMPLE VII A blend was prepared composed of a minor proportion, 5%, of acrylic fiber of the type described in Franch Patent 1,248,314 (3 denier, 4 /2 inch staple), and a major proportion, 95%, of acrylic fiber of the type described in US. Patent 2,837,501 (3 denier/filament prepared on a Turbo- Stapler as described in U.S. Patent 2,419,320). The minor proportion of the fiber has to residual shrinkage while the major proportion of the fiber has only 2% residual shrinkage.

The yarn was spun on the worsted system to 4/ 16s worsted count. The spun yarn, in hanks, was steamed in an autoclave at 240 F. and 10 pounds per square inch pressure for five minutes.

The yarns were then temporarily stretched to almost twice their relaxed length to dissociate the heat-shrunken fibers and then relaxed to their stable tensionless length.

This experiment was repeated using 10% of the high shrinkage acrylic fiber and 90% of the low shrinkage acrylic fiber. The following table shows the average length in centimeters of three one-meter, as-spun samples of each of the above yarns at each stage of the process.

The individual fibers were highly crimped and the final yarns were very bulky, together with a fair degree of stretchability.

Table Samples Blend ratio 5/95 10/90 Alter steam relaxation em 57 51 Maximum stretch em 87 87 After 3 minutes relaxation .cm 60. 5 57 In all the examples, the hanks of yarn were laid on shallow trays in order to secure the tensionless conditions referred to. The hanks in each tray thus had freedom to shrink in length when in the autoclave.

Although the invention has been described so far with particular reference to staple fiber yarn, there is nothing in the present invention that inherently requires the use of such staple fiber yarns, and continuous filament yarns may be used as well as or instead of staple fiber yarns. For instance, a small amount of continuous filament yarn may be fed into the staple fiber blend in order to give any desired effect, Whether an ornamental effeet or any particularly desired textile characteristics. The fiber of high shrinkage power may conveniently be used in the form of a continuous filament, rather than staple fibers. In such circumstances, it may not be practical to neutralize the inextensible nature of the shrunken continuous filament merely by a stretching operation, and alternative methods may have to be used, for instance weakening or even breaking the continuous filament in ermittently by passing the yarn between two rollers, at least one of which is serrated, before carrying out a stretching operation. A suitable apparatus for handling singles or multiple ends of yarn is described in U. S. Patent No. 2,419,320 to James L. Lohrke, frequently referred to as the Turbo-Stapler.

When staple fibers are used as crimp-settable fibers and/ or fibers of high shrinkage power, there is apparently no criticaiity as to fi er length. The fibers may be of the same or different lengths.

As many widely diiferent embodiments of this invention may be made Wtihout departing from the spirit and scope thereof, it is to be understood that this invention is not to be limited to the specific embodiments thereof except as defined in the appended claims.

I claim:

1. A process for preparing a bulky extensible yarn which comprises spinning a yarn comprised of from about 2% to about 20% by weight of synthetic fiber having a shrinkability of at least about 30% and a major proportion by weight of synthetic crimp-scttable fiber, shrinking said fiber of high shrinkability under substantially tensionless conditions to provide a bulky inextensible yarn wherein said crimp-settable fiber is crimped and said shrunken fiber restrains said yarn from longitudinal extension, setting the crimp in said crimped fiber, and thereafter treating said yarn to neutralize the longitudinal restraint imposed by said shrunken fiber by stretching said yarn an amount suificient to displace the shrunken fibers relative to each other and to the crimped fiber, said amount of stretching being not greater than the length of the original spun yarn.

2. The process of claim 1 wherein said crimp-settable fiber is a thermoplastic fiber.

3. The process of claim 2 wherein said fiber of high shrinkability is a polyvinyl chloride fiber.

4. The process of claim 2 wherein said erimp-settable fiber is an acrylonitrile copolymer fiber.

5. The process of claim 2 wherein said shrinking is accomplished by treating said yarn with steam.

6. A process for preparing a bulky extensible yarn which comprises spinning a yarn comprised of a major proportion by weight of synthetic thermoplastic crimpsettable fiber having a shrinkability of less than about 3% and from about 2% to about 20% by weight of a high shrinkage synthetic fiber having a shrinkability from about 30% to about 60%, shrinking said high shrinkage fiber in steam under substantially tensionless conditions to provide a bulky inextcnsible yarn wherein said crimpsettable fiber is crimped and said shrunken fiber rcstrains said yarn from longitudinal extension, setting the crimp in said erimped fiber and thereafter stretching said yarn an amount not greater than the length of the original spun yarn to displace the shrunken fibers relative to each other and to the crimped fiber.

7. The process of claim 6 wherein said high shrinkage fiber is a polyvinyl chloride fiber.

8. The process of claim 7 wherein said crimp-settable fiber is an acrylonitrile copolymer fiber.

9. A bulky extensible yarn comprised of a major proportion of synthetic fibers set with a random three-dimensional crimp and not more than 2% to 20% of substantially uncrimped synthetic fibers, said substantially uncrimped fibers being displaced from each other substantially centrally within the yarn, said yarn having a recoverable elongation of at least about 20%.

10. The yarn of claim 9 wherein said fibers set with a random three-dimensional crimp are acrylonitrile copolymer fibers.

11. The yarn of claim 10 wherein the substantially uncrimped fibers are polyvinyl chloride fibers.

12. The yarn of claim 10 containing 2% to 10% by Weight of polyvinyl chloride fibers and 98% to 90% of acrylonitrile copolymer fibers.

10 13. A yarn of claim 12 having a recoverable elongation of from about 20% to about 50%.

References Cited in the file of this patent UNITED STATES PATENTS 2,450,948 Foster Oct. 12, 1948 2,504,523 Harris et al Apr. 18, 1950 2,701,406 Bloch Feb. 8, 1955 2,789,340 Cresswell Apr. 23, 1957 2,810,281 Appleton et al Oct. 22, 1957 2,985,940 Weldon May 30, 1961 

9. A BULKY EXTENSIBLE YARN COMPRISED OF A MAJOR PROPORTION OF SYNTHETIC FIBERS SET WITH A RANDOM THREE-DIMENSIONAL CRIMP AND NOT MORE THAN 2% TO 20% OF SUBSTANTIALLY UNCRIMPED SYTHETIC FIBERS, SAID SUBSTANTIALLY UNCRIMPED FIBERS BEING DISPLACED FROM EACH OTHER SUBSTANTIALLY CENTRALLY WITHINTHE YARN, SAID YARN HAVING A RECOVERABLE ELONGATION OF AT LEAST ABOUT 20%. 